In many situations it is desirable to have an extendible frame which can be adjusted to a selected position of extension. This is commonly done by utilizing inner and outer tubular members, the inner member being slidably received within the outer member, and providing means to secure the inner member in its selected position.
Many prior art devices have satisfied this requirement in one way or another. There are, however, a number of considerations which are involved if an optimum result is to be obtained. These include the ease of operating the device, the degree of reliability and safety that it provides, the cost of manufacture, and its appearance.
For example, the operation should be such that the frame can be very easily extended, can be easily locked in place, and yet will remain very firmly locked in its extended position. Cost of the manufactured parts should be kept to a minimum. And the device should have a neat appearance.